View Compilation Error

0_0_9218791_23318.cpp:35: error: `stack' does not name a type
0_0_9218791_23318.cpp: In function `void dfs(int)':
0_0_9218791_23318.cpp:39: error: `st' undeclared (first use this function)
0_0_9218791_23318.cpp:39: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_9218791_23318.cpp: In function `void tarjan(int)':
0_0_9218791_23318.cpp:71: error: `st' undeclared (first use this function)
0_0_9218791_23318.cpp: In function `void add_clause(int)':
0_0_9218791_23318.cpp:94: error: `map' undeclared (first use this function)
0_0_9218791_23318.cpp: In function `int main()':
0_0_9218791_23318.cpp:117: error: `map' undeclared (first use this function)